Over the years circular saws have been proposed with specific individual problems in mind, for example, ease of construction, or method of operation, or dust removal, etc.
It has been proposed in U.S. Pat. No. 3,245,439 to make the housing of a portable electric saw in two complementary halves which mate in a plane which includes the rotational axis of the electric motor. Each half includes a half of the motor compartment in which the motor is mounted in clamshell fashion. However, this housing arrangement only provides one open handle by which an operator controls the portable saw.
Circular saws with two handles are known as shown in U.S. Pat. No. 180,815, and still other arrangements are known wherein a handle is in line with the circular saw-blade as shown in U.S. Pat. No. 963,520.
However, all of these arrangements do not give the operator the complete control over the circular saw that may be desirable. For example, in U.S. Design Patent 180,815 both handles are to one side of the saw-blade so that the operator tends to impart a turning moment to the circular saw making it very difficult for the operator to hold precisely on the cutting line of the workpiece. On the other hand, although U.S. Pat. No. 963,520 shows a handle in line with the saw-blade, here there is no second handle and an operator cannot control the unit with both hands.
It has been proposed in German Utility Model Publication No. 588,318 to invert a circular saw and clamp it on a workbench to use it as a table saw. However, the stability of the inverted circular saw, if operated in this way, would require careful consideration.
Various dust extraction arrangements with circular saws have been proposed. In one such arrangement, shown in U.S. Pat. No. 1,888,679, a nozzle extends from the saw-blade compartment rearwardly of the saw and has an adjustable elbow through which the dust can be directed in a desired direction. The dust is discharged by the combination of centrifugal force and the air current created by the revolving blade. However, with such an arrangement only a limited amount of the dust produced may be discharged.
In more improved arrangements, it has been proposed to mount a fan on the armature shaft of the motor and arrange for the fan to draw the dust from the saw-blade housing and discharge it into a dust bag. In this respect German Offenlegungsschrift No. 27 54 186 discloses a portable circular saw having a dust removal system in which one end of the dust bag is connected via a short conduit to the saw-blade compartment forwardly of the motor compartment, and the other end of the dust bag is connected via a longer special conduit to the outer end of the motor compartment containing the fan. Also, German Published Patent Application 7411811 discloses a portable electric saw having a dust removal system with the fan mounted in the outer end of the motor compartment and arranged to draw dust from the saw-blade compartment through a passage specially formed in the motor housing; the dust is then discharged forwardly through a nozzle into a dust bag located in the forward direction ahead of the saw. With both these proposals, dust conduits have to be specially provided; also, the dust bags limit some of the operator's forward view of the workpiece being cut. Further, the saws are not adapted for ease of operation and versatility.